Quote Originally Posted by DennyW
Raced the same guy, same day, twice with another brand, and the third and forth with split fires. The first races (quarter mile mark off here), I lost. You could hear the miss fires at 6 grand, I switched plugs, and beat him the other 2 races. Yes, both sets were new plugs. Yes, I could feel the difference. Response was more solid. No, I don't have any fancy stuff anymore for testing. Only the street.

This was a well known, marked off back road, with guys at both ends to regulate traffic.

Besides, does that dyno have a set climate ? Sunny day dry, cloudy day, wet ?
Well yes,we can control the temp and the humidity .
If you say you can feel the difference the I will have to take your word for it.
I have only done this for 20+ years you have done this for more than 30 years and I could never tell any difference by the seat of the pants by trying different plugs un-less we had the totally wrong ones in there.
I.M.O.,this is something only a dyno could tell.
For all you new guys to engine building there is no such thing as a "magic spark-plug".
The gains are a very small amount and the guy on the street does not need to go out there and spend $7.00 a piece on spark -plugs.